As a manufacturing method of monocrystalline silicon, an MCZ (Magnetic field applied Czochralski) method and a CZ (Czochralski) method requiring no magnetic field application are typically known. In the MCZ method and the CZ method, dislocation may occur in a straight body of the monocrystalline silicon. Accordingly, a solution for avoiding occurrence of dislocation has been studied (see, for instance, Patent Literatures 1 and 2).
In an apparatus of Patent Literature 1 relating the CZ method, a heat radiation body is raised or lowered relative to a heat shield to be positioned at an upper end of a quartz crucible, thereby inhibiting heat radiation from a silicon melt and efficiently transmitting heat of the heat radiation body to the silicon melt via the quartz crucible, so that the silicon melt can be heated to a predetermined temperature using a less electrical power. Moreover, a temperature of an inside, expanding to a lateral upper end, of the quartz crucible can be made uniform, so that the silicon melt can be prevented from adhering on an inner circumferential surface of the upper end of the quartz crucible to inhibit occurrence of dislocation.
In a method of Patent Literature 2 relating to the MCZ method, a step in which the silicon melt is left still while a magnetic field is applied to the silicon melt, and subsequently a step in which the application of the magnetic field is stopped and the silicon melt is left still are conducted after a melting step of melting a polycrystalline silicon and before a pull-up step of growing monocrystalline silicon. By this process, cristobalite is formed on a surface of the quartz crucible in the step in which the silicon melt is left still while a magnetic field is applied to the silicon melt, and subsequently cristobalite is appropriately melted in the step in which the application of the magnetic field is stopped, so that occurrence of dislocation is inhibitable.